A fast Fourier transform (FFT) technique is for converting signals in a time domain into signals in a frequency domain or for converting signals in the frequency domain into signals in the time domain.
The FFT technique has come into widespread use for various digital signal processing fields, such as the communication signal processing field and the image signal processing field.
Particularly, the FFT technique is essential to an OFDM (orthogonal frequency division multiplexing) wireless communication system that is suitable for processing data at a very high speed in a wireless communication environment including a multi-path fading environment.
The size of fast Fourier transform required for various communication fields depends on the specifications of each system.
For example, a communication system, such as ADSL (asymmetrical digital subscriber line), requires a 512-point fast Fourier transform size, and a high-speed portable Internet system, such as WiBro, requires a 1024-point fast Fourier transform size.
In addition, an upgraded WiBro system that will be developed in the near future is expected to selectively use various bands, such as a 10 MHz band, a 20 MHz band, and a 40 MHz band, according to a wireless communication environment and system specifications.
In this case, in order to support the system specifications, each base station needs to have various fast Fourier transform sizes and to output multiple fast Fourier transform data.
For example, four 1024-point fast Fourier transform hardware engines and two 2048-point fast Fourier transform hardware engines are needed to realize a base station system for allowing a wireless communication system to selectively use various bands, such as four 10 MHz bands and two 20 MHz bands, required for the upgraded WiBro system.
In addition, both the 1024-point fast Fourier transform hardware engine and the 2048-pointer fast Fourier transform hardware engine should be provided in order to change to various bands during the connection of a base station.
In order to solve the above-mentioned problems, a method of providing every available fast Fourier transform hardware engine in a base station has been proposed.
However, in this case, some of the fast Fourier transform hardware engines may not be used at all, which results in an increase in the cost of the system. In addition, the method has a problem in that system space is reduced.
Further, a method of using a variable fast Fourier transform hardware engine that supports 1024 points and 2048 points has been proposed.
However, in the variable fast Fourier transform hardware configuration, one 2048-point fast Fourier transform hardware engine is used to form a 1024-point fast Fourier transform hardware engine, which results in unnecessary consumption of hardware resources.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.